Geekpreneur has a nice post on the ways to kill a virtual team fast. these are nice practical tips which all boil down to trust.

• irregular contact – have meetings at regular times, keep regular contact!
• lack of leadership
• lack of responsibility
• sudden disappearances (i kid you not – i had a virtual team leader go on holiday for a week. the person didn’t tell any of the folks outside his office, didn’t have an out of office email set up, and finally on the friday one of his coworkers told us he was on holiday all week. of course we were wondering why our emails weren’t getting replied to!)
• lack of member info (trade IM, facebook, linkedin, etc. mix & match both your communications methods & let them see your world in some way